Office to housing conversion: estimating life cycle environmental and financial performance

The context of this research paper revolves around the growing need for sustainable housing solutions in urban environments. Published in the Journal of Physics: Conference Series, the paper is authored by a team from the Louvain Research Institute for Landscape, Architecture, and Built Environment (LAB) at Université catholique de Louvain, and Saint-Louis University in Brussels. The aim of the study is to evaluate the life cycle environmental and financial performance of repurposing office buildings into residential units.

Renovating existing buildings is often considered more environmentally friendly than demolishing and constructing new ones. However, few studies have quantified the life cycle environmental benefits of such renovations. This research establishes a benchmark through a representative case study, estimating greenhouse gas emissions and financial costs associated with four redevelopment scenarios: (1) renovation as an office; (2) conversion into residential housing; (3) demolition and construction of an office; and (4) demolition and construction of a residential building.

The findings reveal that demolition and construction scenarios have the most significant environmental impact. The office renovation scenario produces only 13% of the impact of the residential demolition-construction scenario, while the housing conversion is at 22%.

The case study focuses on an office building located on rue d'Arlon in Brussels, which spans approximately 11,000 m² and has been vacant for nearly 20 years. The research assesses the building's current state and proposes four scenarios for evaluation. The methodology employed includes financial, technical, environmental, and legal analyses, ensuring that the scenarios are both realistic and representative of the current market.

The life cycle analysis tool used for this study is TOTEM, which evaluates the environmental impacts of construction materials. The key indicator assessed is greenhouse gas emissions, particularly focusing on "climate change" contributions.

The financial analysis shows that while the total costs for renovation and new construction do not vary significantly, converting old office buildings to residential use is generally not financially attractive. The market analysis indicates that developers find it more lucrative to transform old offices into new office spaces rather than into housing.

For instance, an office building with a mean rent of 230€ per square meter could be valued at 57.5 million € for a 10,000 m² space, while a similar residential property would be valued at 45 million €. This financial disparity highlights the challenges of creating affordable housing through office conversions, underscoring the importance of public support and incentives.

The study concludes that the current market dynamics favor office developments over residential conversions due to higher valuation and rental yields. Factors such as the loss of marketable floor space and the complexities involved in project planning further complicate the conversion process.

Recommendations for public authorities include understanding market logics better to define strategies that encourage housing projects through office conversions. By addressing the financial and regulatory challenges, it may be possible to increase the feasibility of turning office buildings into sustainable housing.

This work contributes to the broader discussion on sustainable urban development, providing essential data and insights for policymakers, developers, and researchers focused on improving environmental performance in housing.